On this page, we will take an in-depth look at the primary stage of the In Win Commander III 700 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses two rectifying bridges, which are attached to the same heatsink as the active PFC and switching transistors. The manufacturer, however, scratched the markings on the bridges, so we couldn’t identify them.
The active PFC circuit uses two STW26NM60N MOSFETs, each one supporting up to 20 A at 25° C or 12.6 A at 100° C in continuous mode (note the difference temperature makes), or 80 A at 25° C in pulse mode. These transistors present a 165 mΩ maximum resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.
The output of the active PFC circuit is filtered by two 220 μF x 450 V Japanese electrolytic capacitors, from Panasonic, labeled at 105° C. They are the equivalent of a single 440 μF x 450 V capacitor.
In the switching section, another two STW26NM60N MOSFETs are employed using the traditional two-transistor forward configuration, which is interesting to see, since currently other manufacturers tend to use a resonant configuration for power supplies with the 80 Plus Gold certification. The specifications for these transistors were already discussed above.
The primary is controlled by a CM6802 active PFC/PWM combo controller.
Let’s now take a look at the secondary of this power supply.